This verse, together with John 20:30-31, affirms that this Gospel is the record of selected things that serve the purpose of testifying to the matter of life and building.
In note Matt. 28:202c, para. 2, it is pointed out that the Lord's ascension is not mentioned in John or Matthew. The reason it is not mentioned is that today, after His resurrection, the Lord is still on the earth to be with His believers, and He will be with them until the end of this age, when He will be manifested in His visible glory (1 Pet. 1:7; 2 Thes. 1:7), that is, when He will come back to the earth in His visible presence (Matt. 16:27) to establish His visible kingdom. The Gospel of Matthew unveils and testifies that today, after His resurrection, the Lord, who is the spiritual King of the invisible kingdom of the heavens, is still on the earth in His Spirit of resurrection to be with the people of the kingdom of the heavens in His invisible presence; hence, Matthew does not mention His leaving the earth to ascend to the heavens. The Gospel of John reveals and testifies that as the Triune God, the Lord became flesh (John 1:14) to be the Lamb of God (John 1:29) and, after accomplishing His redemptive death for man, was transfigured in resurrection to become the life-giving Spirit (1 Cor. 15:45) and to enter into those who believe into Him to be their life for eternity, never to be separated from them; hence, it would have been inappropriate for John to mention His going away in ascension.
Furthermore, the four Gospels are a full revelation of how the Triune God came to complete Christ, that is, to make Christ complete. The record in the Gospel of John is crucial regarding this matter. It shows us that the completing of Christ, who was anointed and commissioned by God to accomplish God's eternal will, was carried out by the Triune God becoming flesh in order to be united with man. First, through His death in the flesh He accomplished redemption for man, and then through resurrection He was transfigured to become the Spirit that He might enter into the believers (John 20:22) to be united with them, that they might be united with the Triune God (John 17:21). Thus He became Christ, the embodiment of God, and is able to take away men's sins and enter into men to be their life that they may become the sons of God to be His members, constituting His Body as the full expression of the Triune God. Thus, He is in them to be all their reality and to be with them invisibly until their bodies are redeemed and transfigured that they may enter into His visible presence to be completely united with Him and completely like Him, and to become the New Jerusalem, which is about to be completed, as the mutual habitation of the Triune God and His redeemed people for eternity!